python locals

Python locals() function returns a dictionary representing the current local symbol table.

Python locals（）函数返回一个表示当前本地符号表的字典 。

Python program maintains program information in symbol tables. There are two types of symbol tables:

Python程序在符号表中维护程序信息。 符号表有两种类型：

• Local Symbol Table – stores information related to the local scope of the program. We can get this detail using locals() function.本地符号表–存储与程序的本地范围有关的信息。 我们可以使用locals（）函数获得此详细信息。
• Global Symbol Table – stores information related to the global scope of the program. We can get this detail using globals() function.全局符号表–存储与程序的全局范围有关的信息。 我们可以使用globals（）函数获得此详细信息。

Python symbol table contains details about variable names, methods, classes, etc.

Python符号表包含有关变量名称，方法，类等的详细信息。

Python locals（） (Python locals())

Python locals() function doesn’t take any argument. Let’s see the dictionary returned by locals() function.

Python locals（）函数不带任何参数。 让我们看看locals（）函数返回的字典。

print(locals())

Output:

输出：

{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x10ab79358>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': '/Users/pankaj/Documents/github/journaldev/Python-3/basic_examples/python_locals_example.py', '__cached__': None}

If you will execute print(globals()), you will get the same output. However, the output might vary a little based on your Python installation.

如果执行print(globals()) ，将得到相同的输出。 但是，根据您的Python安装，输出可能会有所不同。

So where is the difference between locals() and globals()?

那么locals（）和globals（）之间的区别在哪里？

There is no difference because we are executing locals() and globals() in the current module itself. The difference will be present when we call these functions inside a method or class.

这没有什么区别，因为我们在当前模块本身中执行locals（）和globals（）。 当我们在方法或类中调用这些函数时，会出现差异。

内部方法的Python locals（） (Python locals() inside method)

Let’s see what is the output when locals() and globals() are invoked inside a function body.

让我们看看在函数体内调用locals（）和globals（）时的输出是什么。

# locals() inside function
def fx1():var = 1global glgl = 'x'print('\nlocals() value inside function\n', locals())print('\nglobals() value inside function\n', globals())fx1()

Output:

输出：

locals() value inside function{'var': 1}globals() value inside function{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x10277c358>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': '/Users/pankaj/Documents/github/journaldev/Python-3/basic_examples/python_locals_example.py', '__cached__': None, 'fx1': <function fx1 at 0x1027141e0>, 'gl': 'x'}

So it’s clear that locals() inside function returns the local variable, notice that global variables are part of global symbol table dictionary.

因此很明显，函数内部的locals（）返回了局部变量，请注意，全局变量是全局符号表字典的一部分。

类内部的Python locals（） (Python locals() inside class)

Let’s see the output when locals() is called inside class body.

让我们看看在类体内部调用locals（）时的输出。

# locals() inside class
class Data:x = 0print('\nlocals() value inside class\n', locals())print('\nglobals() value inside class\n', globals())

Output:

输出：

locals() value inside class{'__module__': '__main__', '__qualname__': 'Data', 'x': 0}globals() value inside class{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x10277c358>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': '/Users/pankaj/Documents/github/journaldev/Python-3/basic_examples/python_locals_example.py', '__cached__': None, 'fx1': <function fx1 at 0x1027141e0>, 'gl': 'x'}

When invoked inside the class body, locals() contains the module name, class name and class variables.

在类主体中调用时，locals（）包含模块名称，类名称和类变量。

结论 (Conclusion)

Python locals() function is mostly used for debugging purpose. We can check what variables are present in the local scope and their values. We can also alter their values since it’s a dictionary, although not recommended.

Python locals（）函数主要用于调试目的。 我们可以检查本地范围内存在哪些变量及其值。 由于它是字典，因此我们也可以更改其值，尽管不建议这样做。

Reference: Official Documentation

参考： 官方文档

翻译自: https://www.journaldev.com/22946/python-locals

python locals